Effect of combined flexion and external rotation on measurements of the proximal femur from anteroposterior pelvic radiographs.

INTRODUCTION: Fixed flexion and external rotation contractures are common in patients with hip osteoarthritis and, in particular, before total hip replacement (THR). We aimed to answer the following question: how does combined flexion and external rotation of the femur influence the radiographic assessment of (1) femoral offset (FO) (2) neck-shaft angle (NSA) and (3) distance (parallel to the femoral axis) from greater trochanter to femoral head center (GT-FHC)? HYPOTHESIS: Combined flexion and external rotation impact the accuracy of two-dimensional (2D) proximal femur measurements. MATERIALS AND METHODS: Three-dimensional (3D) CT segmentations of the right femur from 30 male and 42 female subjects were acquired and used to build a statistical shape model. A cohort (n=100; M:F=50:50) of shapes was generated using the model. Each 3D femur was subjected to external rotation (0°-50°) followed by flexion (0°-50°) in 10° increments. Simulated radiographs of each femur in these orientations were produced. Measurements of FO, NSA and GT-FHC were automatically taken on the 2D images. RESULTS: Combined rotations influenced the measurement of FO (p<0.05), NSA (p<0.001), and GT-FHC (p<0.001). Femoral offset was affected predominantly by external rotation (19.8±2.6mm [12.2 to 26.1mm] underestimated at 50°); added flexion in combined rotations only slightly impacted measurement error (20.7±3.1mm [13.2 to 28.8mm] underestimated at 50° combined). Neck-shaft angle was reduced with flexion when external rotation was low (9.5±2.1° [4.4 to 14.2°] underestimated at 0° external and 50° flexion) and increased with flexion when external rotation was high (24.4±3.9° [15.7 to 31.9°] overestimated at 50° external and 50° flexion). Femoral head center was above GT by 17.0±3.4mm [3.9 to 22.1mm] at 50° external and 50° flexion. In contrast, in neutral rotation, FHC was 12.2±3.4mm [3.9 to 22.1mm] below GT. DISCUSSION: This investigation adds to current understanding of the effect of femoral orientation on preoperative planning measurements through the study of combined rotations (as opposed to single-axis). Planning measurements are shown to be significantly affected by flexion, external rotation, and their interaction. LEVEL OF EVIDENCE: IV Biomechanical study.

A net carbohydrate and protein system for evaluating cattle diets: IV. Predicting amino acid adequacy.

The Cornell Net Carbohydrate and Protein System was modified to include an amino acid submodel for predicting the adequacy of absorbed essential amino acids in cattle diets. Equations for predicting the supply of and requirements for absorbed essential amino acids are described and presented. The model was evaluated for its ability to predict observed duodenal flows of nitrogen, nonammonia nitrogen, bacterial nitrogen, dietary nonammonia nitrogen, and individual essential amino acids. Model-predicted nitrogen, nonammonia nitrogen, bacterial nitrogen, and dietary nonammonia nitrogen explained 93.2, 94.6, 76.4, and 79.3% of the observed duodenal flows, respectively, based on R2 values from predicted vs observed regression analysis. Based on slopes of regression lines, model-predicted duodenal nitrogen and nonammonia nitrogen were different from observed duodenal flows (P < .05), whereas model-predicted bacterial nitrogen and dietary nonammonia nitrogen were not different from observed duodenal flows (P < .05). Model-predicted duodenal flows of individual essential amino acids explained 81 to 90% of variation in observed duodenal amino acid flows. Based on slopes of regression lines, model-predicted duodenal threonine, leucine, and arginine were the only amino acids different from observed duodenal flows (P < .05). Ideas for further model improvements and research in amino acid metabolism were also presented.

Hypothyroidism in the elderly: clinical assessment versus routine screening.

A total of 304 patients aged 65 years or over were prospectively studied over a four-month period to assess whether clinical findings or routine screening were more helpful in diagnosing biochemical hypothyroidism. The most useful symptom relevant to a possible diagnosis of hypothyroidism in the elderly was found to be dry skin. Dermatological signs and certain ECG abnormalities (especially atrial fibrillation) were helpful when querying a diagnosis of hypothyroidism. Almost 50% of patients receiving amiodarone had abnormal thyroid function tests (TFTs). Routine screening for hypothyroidism does not seem justifiable from our available data although this conclusion may have been different had hospital clinicians and general practitioners followed their patients up more closely after an initial abnormal result was obtained.

A net carbohydrate and protein system for evaluating cattle diets: III. Cattle requirements and diet adequacy.

The Cornell Net Carbohydrate and Protein System (CNCPS) has equations for predicting nutrient requirements, feed intake, and feed utilization over wide variations in cattle (frame size, body condition, and stage of growth), feed carbohydrate and protein fractions and their digestion and passage rates, and environmental conditions. Independent data were used to validate the ability of the CNCPS to predict responses compared to National Research Council (NRC) systems. With DMI in steers, the CNCPS had a 12% lower standard error of the Y estimate (Sy.x) and three percentage units less bias than the NRC system. For DMI in heifers, both systems had a similar Sy.x but the NRC had four percentage units less bias. With lactating dairy cows' DMI, the CNCPS had a 12% lower Sy.x. Observed NEm requirement averaged 5% under NRC and 6% under CNCPS predicted values at temperatures above 9 degrees C but were 18% over NRC and 9% under CNCPS at temperatures under 9 degrees C. Energy retained was predicted with an R2 of .80 and .95 and a bias of 8 and 4% for the NRC and CNCPS, respectively. Protein retained was predicted with an R2 of .75 and .85 with a bias of 0 and -1% for NRC and CNCPS, respectively. Biases due to frame size, implant, or NEg were small. Body condition scores predicted body fat percentage in dairy cows with an R2 of .93 and a Sy.x of 2.35% body fat. The CNCPS predicted metabolizable protein allowable ADG with a bias of 1.6% with a Sy.x of .07 kg compared to values of -30% and .10 kg, respectively for the NRC system.

A net carbohydrate and protein system for evaluating cattle diets: I. Ruminal fermentation.

The Cornell Net Carbohydrate and Protein System (CNCPS) has a kinetic submodel that predicts ruminal fermentation. The ruminal microbial population is divided into bacteria that ferment structural carbohydrate (SC) and those that ferment nonstructural carbohydrate (NSC). Protozoa are accommodated by a decrease in the theoretical maximum growth yield (.50 vs .40 g of cells per gram of carbohydrate fermented), and the yields are adjusted for maintenance requirements (.05 vs .150 g of cell dry weight per gram of carbohydrate fermented per hour for SC and NSC bacteria, respectively). Bacterial yield is decreased when forage NDF is < 20% (2.5% for every 1% decrease in NDF). The SC bacteria utilize only ammonia as a N source, but the NSC bacteria can utilize either ammonia or peptides. The yield of NSC bacteria is enhanced by as much as 18.7% when proteins or peptides are available. The NSC bacteria produce less ammonia when the carbohydrate fermentation (growth) rate is rapid, but 34% of the ammonia production is insensitive to the rate of carbohydrate fermentation. Ammonia production rates are moderated by the rate of peptide and amino acid uptake (.07 g of peptide per gram of cells per hour), and peptides and amino acids can pass out of the rumen if the rate of proteolysis is faster than the rate of peptide utilization. The protein-sparing effect of ionophores is accommodated by decreasing the rate of peptide uptake by 34%. Validation with published data of microbial flow from the rumen gave a regression with a slope of .94 and an r2 of .88.

A net carbohydrate and protein system for evaluating cattle diets: II. Carbohydrate and protein availability.

The Cornell Net Carbohydrate and Protein System (CNCPS) has a submodel that predicts rates of feedstuff degradation in the rumen, the passage of undegraded feed to the lower gut, and the amount of ME and protein that is available to the animal. In the CNCPS, structural carbohydrate (SC) and nonstructural carbohydrate (NSC) are estimated from sequential NDF analyses of the feed. Data from the literature are used to predict fractional rates of SC and NSC degradation. Crude protein is partitioned into five fractions. Fraction A is NPN, which is trichloroacetic (TCA) acid-soluble N. Unavailable or protein bound to cell wall (Fraction C) is derived from acid detergent insoluble nitrogen (ADIP), and slowly degraded true protein (Fraction B3) is neutral detergent insoluble nitrogen (NDIP) minus Fraction C. Rapidly degraded true protein (Fraction B1) is TCA-precipitable protein from the buffer-soluble protein minus NPN. True protein with an intermediate degradation rate (Fraction B2) is the remaining N. Protein degradation rates are estimated by an in vitro procedure that uses Streptomyces griseus protease, and a curve-peeling technique is used to identify rates for each fraction. The amount of carbohydrate or N that is digested in the rumen is determined by the relative rates of degradation and passage. Ruminal passage rates are a function of DMI, particle size, bulk density, and the type of feed that is consumed (e.g., forage vs cereal grain).

Characterization and partial purification of the Drosophila Kc cell ecdysteroid receptor.

The molting hormones of insects, the ecdysteroids, are steroids whose action is mediated by an intracellular receptor. The Kc cell line of Drosophila melanogaster possesses ecdysteroid receptors and exhibits characteristic, receptor-dependent morphological and biochemical responses to the application of ecdysteroids. This paper describes the interaction of muristerone A (2 beta, 3 beta, 5 beta, 11 alpha, 14 alpha(20R,22R)- heptahydroxycholest-7-en-6-one), a phytoecdysteroid, with the Kc cell ecdysteroid receptor. Muristerone A-receptor complexes are not as sensitive to dissociation in high salt buffers as other ecdysteroid-receptor complexes we have examined. This has enabled us to use [3H]muristerone A to follow the Kc cell ecdysteroid receptor during heparin-agarose, DNA-cellulose, and hydroxylapatite chromatography, as well as gel filtration and ion exchange high pressure liquid chromatography. The Drosophila Kc cell ecdysteroid receptor has a Stokes radius of 4.6 nm, a frictional coefficient of 1.4, and a molecular weight of 120,000. A procedure is presented that results in a 750-fold enrichment of the receptor.

Modulation of novel-length DOPA decarboxylase transcripts by 20-OH-ecdysone in a Drosophila melanogaster Kc cell subline.

The induction of DOPA decarboxylase (DDC) activity by 20-OH-ecdysone (20-OHE) in a subline of Drosophila melanogaster Kc cells was investigated. Cells cultured in the continuous presence of the steroid hormone exhibited a 96-h temporal lag prior to a peak of DDC enzyme activity while arrested in the G2 phase of the cell cycle. The concentration of Ddc RNA increased sixfold between 72 and 96 h after initial exposure to hormone. Similarly, this increase was correlated temporally with a 26-fold increase in DDC enzyme activity. The Kc Ddc primary transcript, processing intermediate, and mature mRNA all were approximately 500 nucleotides longer than the corresponding transcripts observed for newly eclosed adult D. melanogaster. In vitro translation of poly(A)+ RNA from Kc cells resulted in an immunoprecipitable polypeptide which exhibited similar mobility on sodium dodecyl sulfate gels to that of DDC synthesized in vitro by larval epidermal poly(A)+ RNA.

Physiochemical study of rock crab lipoproteins.

Physicochemical studies have been carried out on the hemolymph and egg lipoproteins of the rock crab (Cancer antennarius). Analytical ultracentrifugal analyses of vitellogenic female HDL3 revealed the presence of two types of lipoproteins. The first with a sedimentation rate of 5.35 S was comparable to lipoproteins in male and non-vitellogenic female hemolymph. The second with a sedimentation rate of 10.74 S was comparable to the major lipoprotein of egg yolk. A similar comparison could be made following electrophoretic analyses in native polyacrylamide gels. Electrophoresis in SDS-polyacrylamide gels revealed three major apolipoproteins common to egg and vitellogenic HDL3. A fourth apolipoprotein was found in both male and female HDL3. In contrast to mammalian HDL, none of these crustacean apolipoproteins had a molecular weight less than 82 000. One of these apolipoproteins appears to be comparable physicochemically to the enteric form of apolipoprotein B in mammals.

A novel form of DOPA decarboxylase produced in drosophila cells in response to 20-hydroxyecdysone.

Two cloned derivatives of the Kc cell line of Drosophila were shown to produce DOPA decarboxylase following administration of the steroid moulting hormone 20-hydroxyecdysone. In the continuous presence of the hormone at a concentration of 2 X 10(-7) M, DOPA decarboxylase activity first appeared between 48 and 72 h. Because of this lag, the tissue culture system promises to serve as a useful model for those in vivo situations where increases in the hormone titre precede increases in DOPA decarboxylase activity. In clone 7C4, after maximal enzyme activity was achieved at 144 h, the enzyme activity per cell decreased as the cells resumed division following the hormone-induced division arrest. In clone 7E10, cell division never resumed in the presence of 20-hydroxyecdysone and DOPA decarboxylase activity per cell increased continuously from the time it first appeared. When line 7E10 was exposed to a 6-h pulse of the steroid, enzyme activity appeared about 18 h earlier than in the presence of continuous hormone and, further, the cells were released from division arrest. Enzyme activity per cell then declined from an early 96-h maximum. The enzyme produced by the cell lines was immunologically distinct from the enzyme produced in vivo and ion-exchange column chromatography resolved the enzyme from cells and intact organisms into two species.(ABSTRACT TRUNCATED AT 250 WORDS)

Characterization of ecdysteroid receptors in cytosol and naive nuclear preparations of Drosophila Kc cells.

Significant ecdysteroid binding activity can be demonstrated in nuclear extracts obtained from hormonally naive Drosophila Kc cells. The kinetic and physical characteristics of this nuclear binding are presented and compared with those exhibited by a high speed cytosol preparation of Kc cells. Examination of the effect of in vivo ecdysteroid exposure on the number of nuclear binding sites revealed that the quantity of nuclear receptors was not detectably altered. In addition, an effective synthesis of the biologically active ecdysteroid radioligand, [3H]ponasterone A, is described.

An ecdysteroid-induced alteration in the cell cycle of cultured Drosophila cells.

The addition of physiological concentrations of the arthropod molting hormone 20-hydroxyecdysone results in the cessation of cell division in the Kc cell line of Drosophila melanogaster. Fluorometric mononitoring of the cell cycle reveals that treatment of the cells with hormone for 12 hr causes a G2 arrest. The dose-response curves are in agreement with those obtained for other hormonal effects in both the Kc line and the intact animal. In the continual presence of hormone, cells remain G2-arrested for approximately 100 hr, resuming division by 120 hr. Cells which have responded once to ecdysteroids and subsequently reentered the cell cycle are insensitive to hormonal restimulation. This lack of response has been correlated with, and is probably due to, the loss of ecdysteroid receptors in stimulated cells.

Juvenile hormone-binding protein from the cytosol of Drosophila Kc cells.

Insect cells of an established line, Drosophila Kc cells, take up and metabolize juvenile hormone (JH). The cytoplasm of these cells contains a protein that binds JH with specificity, saturability, and high affinity (K(d) = 1.56 x 10(-8) M). The kinetics for the specific binding and dissociation of JH I were independently measured, and the rate constants were found to be k(a) = 1.3 x 10(6) M(-1) min(-1), k(d) = 1.3 x 10(-2) min(-1), respectively. All three juvenile hormones bind to the protein with comparable affinities; the corresponding acid or diol metabolites of JH I are not bound. About 2500 hormone-binding protein molecules are present per cell. The protein has a molecular weight of 80,000 as estimated by gel permeation chromatography and by sucrose gradient sedimentation. The properties of this protein suggest that it functions as a cytoplasmic receptor for juvenile hormone.

Induction of translatable mRNA for dopa decarboxylase in Drosophila: an early response to ecdysterone.

Ecdysteroid titer and dopa decarboxylase (aromatic-L-amino-acid carboxy-lyase, EC 4.1.1.28) activity were determined throughout the life cycle of Drosophila melanogaster. Five peaks in the amount of hormone were observed, which preceeded five dopa decarboxylase peaks by times ranging from 5 to 58 hr. Late in the third instar the hormone and enzyme maxima are nearly coincident. The increase in enzyme activity observed at this time is paralleled by an increase in translatable dopa decarboxylase mRNA. To obtain evidence that ecdysterone induces the appearance of this mRNA we made use of the temperature-sensitive ecd1 mutant. Garen et al. [Garen, A., Kauvar, L. & Lepesant, J.-A. (1977) Proc. Natl, Acad. Sci. USA 74, 5099-5103] have shown that when third instar mutant larvae are kept at 29 degrees C, the ecdysteroid titer remains low. In such larvae we show that the normal increase in dopa decarboxylase activity fails to appear, and no translatable dopa decarboxylase mRNA can be detected. Exogenous feeding of ecdysterone to these larvae results in a rapid synthesis of dopa decarboxylase in the epidermal cells. In addition, a parallel increase in translatable dopa decarboxylase mRNA occurs, which may be a primary response of these target cells to ecdysterone.